1. Field of the Invention
The present invention relates to a processing system, such as a work processor, which has a printer using an exchangeable ink ribbon which prints documents including characters, symbols, ruled lines or graphic patterns.
2. Description of Related Prior Arts
In a processing system such as a word processing system, a printer is used for printing such things as characters, symbols, and graphic patterns on material such as a sheet of paper. The printer often uses a one-time ink ribbon incorporated within a cassette. For example, as described in U.S. Pat. No. 4,387,380, a thermal transfer printing system uses the one-time ink ribbon cassette wherein a ribbon tape of polyester is coated with pigment or dye such as carbon black which is dispersed in a heat fusible binder.
When using the one-time ink ribbon for printing, the ink ribbon must be exchanged for a new one once it has been exhausted from the leading through trailing ends. Therefore the printer using such one-time ink ribbon usually includes a ribbon-end detector which detects the trailing end of the ink ribbon (hereinafter called "the end of the ink ribbon" for short) Upon such detection printing stops, to stop printing and the processing system asks the operator to exchange the ink ribbon for a new one, since that ink ribbon has been used up. One type of ribbon-end detector having photo couplers is described in U.S. Pat. No. 4,387,380; another type of ribbon-end detector is disclosed in Japanese patent (Tokkai-Sho) No. 58-59886.
One example, includes coating the base film of the end portion of the ink ribbon. The pigment-coated portion of the ribbon cannot reflect light, but the metal-coated portion can. In the printer a luminous diode, acting as a light source and a photo transistor, acting as a light sensor are provided so that the photo transistor can sense light from the luminous diode reflected by the metal coated portion of the ink ribbon. A sense signal is only generated when the ink ribbon has been used up and the metal-coated portion of the ribbon comes in front of the luminous diode. The printing system then recognize the exhaustion of the ink ribbon and then stop printing The operator can now exchange the exhausted ink ribbon, or ink ribbon cassette, for a new one.
In a conventional processing system, however, when the ink ribbon is used up and replaced in the middle of printing a line in a document page, the document must be printed again from a print-start position as the top of the page of the start of the unfinished line. The sheet where a portion of the document page had already been printed must be thrown away, and a new sheet inserted.